1. Field of the Invention
The disclosure relates to a liquid crystal display (LCD) apparatus and a method of manufacturing the same, and more particularly to an LCD apparatus for enhancing display quality and a method of manufacturing the same
2. Description of the Related Art
Electronic display devices convert an electric signal outputted from various electronic devices into an optical signal visually perceived by users.
Recently, there is an increased requirement for flat panel display devices that have a thin and light structure and use a low driving voltage and a low power.
Liquid crystal display (LCD) devices are the most widely used type of the flat panel display devices because the LCD devices are much thinner and use much less power and driving voltage.
FIG. 1 is a cross-sectional view showing a general LCD panel, and FIG. 2 is a schematic view showing a process for forming an alignment layer on a TFT (Thin Film Transistor) substrate of FIG. 1.
Referring to FIG. 1, an LCD panel 90 includes a thin film transistor (TFT) substrate 60, a color filter substrate 70 facing the TFT substrate 60, and a liquid crystal layer 80 interposed between the TFT substrate 60 and the color filter substrate 70.
The TFT substrate 60 includes a first substrate 10, TFTs 20 formed on the first substrate 10, an organic insulating layer 30 formed on the first substrate 10 having the TFTs 20, a pixel electrode 40 formed on the organic insulating layer 30, and a first alignment film 50 formed on the pixel electrode 40.
Each of the TFTs 20 includes a gate electrode 21, a source electrode 25 and a drain electrode 26. The gate electrode 21 is insulated from the source electrode 25 and the drain electrode 26 by a gate insulating layer 22. An active pattern 23 and an ohmic contact pattern 24 are formed on the gate insulating layer 22 so that the source electrode 25 is electrically connected to the drain electrode 26 through the active pattern 23 and the ohmic contact pattern 24 in response to an electric power applied to the gate electrode 21. The source electrode 25 and the drain electrode 26 are formed on the active pattern 23 and the ohmic contact pattern 24.
The organic insulating layer 30 is formed on the TFTs 20. A contact hole 35 is formed on the organic insulating layer 30 to expose the drain electrode 26. The pixel electrode 40 is uniformly formed on the organic insulating layer 30, the drain electrode 26 exposed through the contact hole 35 and the sidewalls of the contact hole 35. The first alignment film 50 is formed on the pixel electrode 40, and has a plurality of alignment grooves (not shown) extended in a predetermined direction or a rubbing direction.
The color filter substrate 70 includes a second substrate 71, color filters 72, a common electrode 73 and a second alignment film 74. The common electrode 73 faces the pixel electrode 40 to be opposite to the TFT substrate 60. The color filter substrate 70 is coupled to the TFT substrate 60 to face each other, and the liquid crystal layer 80 is interposed between the color filter substrate 70 and the TFT substrate 60.
The liquid crystal is aligned in a predetermined direction so that light passes through the liquid crystal layer 80. The liquid crystal is aligned by the first and the second alignment films (50, 74). Hereinafter, the process for forming the first alignment film 50 is described.
Referring to FIG. 2, a polyimide thin film 51 is deposited on the pixel electrode 40. The thin film 51 is formed as a first alignment film 50 having a plurality of alignment grooves 50a through a rubbing process. A rubbing fabric (or rubbing cloth) 56 having a plurality of rubbing piles 56a is attached to an outer surface of a rubbing roller 55. When the rubbing roller 55 is disposed on the thin film 51 and is moved in a predetermined direction or a rubbing direction, the thin film 51 is rubbed by the rubbing piles 56a. Accordingly, the alignment grooves 50a are formed on the thin film 51 along the direction in which the rubbing roller 55 moves. An alignment groove may not be formed when other rubbing process is performed on the thin film 51.
However, the thin alignment grooves 50a may not be formed on the thin film 51 deposited on the contact hole 35, because the alignment is incompletely made at the sidewalls of the contact hole 35 due to a stepped surface of the contact hole 35. Light leakage phenomenon may occur in a black mode of the LCD device because the liquid crystal is incompletely aligned near the contact hole 35. Therefore, the display quality of the LCD device is deteriorated.